Magnetostrictive transducer



P 1965 CHANG-SUN CHANG 3,207,958

MAGNETOSTRI CT IVE TRANSDUCER Filed 001;. 11, 1961 2 Sheets-Sheet 1 29o Flg. I

JET \50 (PIPE 4 34+ qqylafi tu 560 I K 40 Fug. 2

INVENTOR. CHANG S. CHANG ATTORNEY p 1965 CHANG-SUN CHANG 3,207,958

MAGNETOSTRICTIVE TRANSDUCER Filed Oct. 11, 1961 2 Sheets-Sheet 2 U 1 o T I60 120 so 40 0 40 80 I20 I60 CURRENT- MILLIAMPERES 1, H9. 4

INVENTOR. CHANG s. CHANG ATTORNEY United States Patent 3,207,958 MAGNETOSTRICTIVE TRANSDUCER Chang-Sun Chang, Oakland, Mich., assignor to The Bendix Corporation, Southfield, Mich., a corporation of Delaware Filed Oct. 11, 1961, Ser. No. 144,510 7 Claims. (Cl. 317143) This invention pertains to magnetostrictive transducers and more particularly to such a transducer having two spaced rings of bimetallic material each having layers of a positive and negative mangetostrictive material bonded together. Each ring is subject to interacting flux paths from two magnetic circuits, at least one of the magnetic circuits causing a variable flux level to cause a variable elliptical distortion of the rings.

.In certain applications such as a jet pipe movement in a servo valve, extremely accurate and small movements of the jet pipe relative to the servo valve are desired and this movement is not easily obtainable. This invention provides a motor for movement of the jet pipe by utilizing two spaced coaxial rings each being formed of a well-known material which is a bimetallic strip having layers of positive and negative magnetostrictive material, so that when magnetic fields are applied to the strips they will distort, moving a jet pipe which is attached to the circumference of one of the rings.

. In a preferred embodiment the spaced, coaxial rings are connected to each other with permanent magnet bars providing a constant or bias level of magnetic flux in the rings. The rings are also connected to each other with an electromagnetic source which provides a variable magnetic field in the rings. The flux from the permanent magnet interacts with the flux from the electromagnet to provide sections of the rings in which the flux paths reinforce one another and sections where they diminish one another to cause an ellipitical distortion of the rings.

These and other objects will become more apparent When -a preferred embodiment of my invention is described in connection with the drawings in which:

FIGURE 1 is a schematic view illustrating the principle of the invention:

FIGURE 2 is a schematic sectioned view of a preferred embodiment of my invention;

FIGURE 3 is a top view of the embodiment shown in FIGURE 2; and

FIGURE 4 which is a graph of input current vs. output movement of a device made in accordance with this invention.

The principle of this invention is illustrated in and will be explained in reference to the explanatory view in FIGURE 1.

In FIGURE 1 are shown two bimetallic rings 20 and 22, each of which has an outer layer of nickel 20a and 22a, or other negative magnetostrictive material, and an inner layer 20b and 22b of Invar (36% nickel iron alloy), or other positive magnetostrictive material. In the preferred embodiment these rings are .01 inch thick, .1 inch wide with a ring diameter of 2.0 inches. Connected between the tops of the rings is a permanent magnet 24 having its north pole at the left end and connected between the bottoms of the rings a permanent magnet 26 having its north pole at the right end. This provides a constant bias level of flux in the rings which starts from the north pole of the permanent magnets and ends at the south pole so that in ring 22; the flux would start at the bottom of the ring and is carried along upwardly on either side to the top of the ring, as indicated by arrows A and B. Conversely, the bias flux in ring 20 would start at the top of the ring and end at the bottom, as indicated by arrows A and B.

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An electromagnet 28 having input winding 29 energized by variable voltage source 29a, is connected to the outer sides of rings 20 and 22 while a soft iron bar 27 is connected between the inner sides of rings 20 and 22 and provides a magnetic field from one side along the upper and lower portions to the other side as indicated by arrows C and D.

Ring 22 is shown divided into four quarters, E, F, G and H. The magnetic flux in quarter E would be diminished since arrow C and arrow B, or the fields from the electromagnet and the permanent magnets, are in opposition in this quarter. This is also true in quarter G where arrows D and A are in opposite directions. However, in quarters F and H the flux from the electromagnet and permanent magnet fields reinforce one another. This tends to distort ring 22 to the elliptical form shown by the dotted lines 22. Of course the ellipse would be turned degrees if the arrows C and D were in the opposite directions which would result if the control current through the winding on electromagnet 28 were reversed.

Both rings 20 and 22 would distort together, thereby shifting bar 30 toward the right a small predetermined amount depending on the control current in the winding of electromagnet 28. The bar could be shifted toward the left by reversing the fields or current in the winding of electromagnet 28. Output movement in inches is shown vs. input current in milliamperes of an embodiment of this invention in FIGURE 4.

A preferred'embodiment adapted for use to direct a jet pipe valve is shown in FIGURES 2 and 3. Here the rings 30 and 32 are coaxial and spaced by 0.8 inch. The rings are supported at their bottom portions by ends 34, 36 of a soft iron inverted U-shaped member 38 which is in turn flexibly supported at 34a and 36a, respectively, by a non-magnetic housing 40. Member 38 has a winding 44 which is attached to a variable direct current voltage source 46.

Passing through the center of core 38 is a jet pipe 48 which is attached at a point on the outer circumference of ring 32.

Connected between two top points of rings 32 is a soft iron bar 50 which forms a path in the magnetic circuit developed when coil 44 is energized. Connected between rings 30 and 32 on the left side, looking at FIG- URE 3, is a permanent magnet 52 having its north pole connected to ring 32 and connected between the rings on the right side is a permanent magnet 54 having its south pole connected to ring 32 which together form a constant bias level of magnetic flux through the rings.

When coil 44 is energized, reinforcing and opposing fluxes are set up in rings 30 and 32 as described for rings 20 and 22 in FIGURE 1, moving the jet pipe 48 to the right or left, as shown in FIGURE 3, depending on which direction the coil 44 is energized and in an amount corresponding to the amount of energization of coil 44.

Although this invention has been disclosed and illustrated with reference to a particular application, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the field. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described my invention, I claim:

1. A magnetostrictive transducer for changing electrical signals to discrete minute mechanical movements comprising an electrical signal input,

at least two bimetallic members, each having a positive magnetostrictive layer and a negative. magnetostrictive layer bonded together,

first and second magnet means for generating magnetic fields in said bimetallic members to provide interacting magnetic fields in each of said bimetallic members and to provide in each of said bimetallic members areas in which the magnetic flux from said first and second magnet means is mutually reinforcing and areas in which the magnetic flux from said first and second magnet means is mutually opposing, thereby distorting both of said bimetallic members in a similar manner,

means energized by said electrical signal input to control the flux from at least one of said first and second magnet means thereby controlling said distortion of said bimetallic members a corresponding and proportional degree.

2. The transducer of claim 1 with said first and second magnet means comprising,

first and second magnet sources, low reluctance first conduit means being between said first magnet source and first spaced points-on each said first-magnet source being connected at two pointsto each of said bimetallic members,

said second magnet source being connected at two points to each of said bimetallic members;

5. The transducer of claim 1, with said bimetallic members each comprising a ring having an outer layer and an inner layer of oppositely polarized magnetostrictive material.

6. The transducer of claim 5, with said first and second magnet means comprising,

first and second magnet sources,

flux conduits being connected to said first and second magnet sources,

the flux of said first magnet source being connected through said conduits to a plurality of first points on each of said rings and the flux of said second magnet source being connected through said conduits to a plurality of second points on each of said rings with said first and second points being alternately located on said rings.

7. The transducer of claim 6 with said rings being spaced in coaxial relation,

a jet pipe extending between said rings and along the axis of said rings, and then at one of said rings extending radially outwardly from said axis to the,

circumference of said one of said rings,

the jet pipe having one end connected to the circumference of said one of said rings,

said rings being flexibly supported so that said jet is movable in a direction tangential to said ring as said means to control the flux from atleast one of said first and second magnets varies theflux from said:

one of said magnets.

References Cited by the Examiner UNITED STATES PATENTS 1,882,397 10/32 Pierce 3l7-143 X 2,696,590 12/54 Roberts 31026 X 3,003,239 10/61 Weidner et al. 31026 X 3,015,708 1/62 Mason 3l7143 X SAMUEL BERNSTEIN, Primary Examiner. 

1. A MAGNETOSTRICTIVE TRANSDUCER FOR CHANGING ELECTRICAL SIGNALS TO DISCRETE MINUTE MECHANICAL MOVEMENTS COMPRISING AND ELECTRICAL SIGNAL INPUT, AT LEAST TWO BIMETALLIC MEMBERS, EACH HAVING A POSITIVE MAGNETOSTRICTIVE LAYER AND A NEGATIVE MAGNETOSTRICTIVE LAYER BONDED TOGETHER, FIRST AND SECOND MAGNET MEANS FOR GENERATING MAGNETIC FIELDS IN SAID BIMETALLIC MEMBERS TO PROVIDE INTERACTING MAGNETIC FIELDS IN EACH OF SAID BIMETALLIC MEMBERS AND TO PROVIDE IN EACH OF SAID BIMETALLIC MEMBERS AREAS IN WHICH THE MAGNETIC FLUX FROM SAID FIRST AND SECOND MAGNET MEANS IS MUTUALLY REINFORCING AND AREAS IN WHICH THE MAGNEFTIC FLUX FROM SAID FIRST AND SECOND MAGNET MEANS IS MUTALLY OPPOSING, 